Shellshock

Shellshock

- 리눅스 계열 및 MAC OS X 운영체제에서 사용되는 GNU Bash shell에서 발견된 취약점

- bash shell에서 export -f 옵션을 이용해 함수를 환경변수로 등록 가능

- f 옵션 없이도 '() {' 로 시작하는 문자열을 환경변수에 저장하면 해당 환경변수 이름을 갖는 함수로 선언됨

- 이 때 함수 선언문 (){ .... } 뒤의 문자열(임의의 명령어)이 계속 실행됨

- 환경변수의 입력값을 처리하는 함수에서, 처리하려는 명령어가 함수 선언문 뒤에 삽입되어 있는지 확인하는 조건문이 없어서 다른 명령어들과 동일하게 처리함. => 명령어가 실행됨

- 입력값 검증 미흡

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CVE-2014-6271

 GNU Bash through 4.3 processes trailing strings after function definitions in the values of environment variables, which allows remote attackers to execute arbitrary code via a crafted environment, as demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution, aka "ShellShock."

 NOTE: the original fix for this issue was incorrect; CVE-2014-7169 has been assigned to cover the vulnerability that is still present after the incorrect fix.

 

 

CVE-2014-7169

 GNU Bash through 4.3 bash43-025 processes trailing strings after certain malformed function definitions in the values of environment variables, which allows remote attackers to write to files or possibly have unknown other impact via a crafted environment, as demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution.

 NOTE: this vulnerability exists because of an incomplete fix for CVE-2014-6271.

 

CVE-2014-6277

 GNU Bash through 4.3 bash43-026 does not properly parse function definitions in the values of environment variables, which allows remote attackers to execute arbitrary code or cause a denial of service (uninitialized memory access, and untrusted-pointer read and write operations) via a crafted environment, as demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution.

 NOTE: this vulnerability exists because of an incomplete fix for CVE-2014-6271 and CVE-2014-7169.

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 HackSum

 

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보안뉴스 : 배시라이트 멀에워(사물인터넷 멀웨어)

배시라이트 멀웨어, 암호화폐 채굴과 백도어 기능으로 업그레이드